[syslinux] Inconsistencies between ExtLinux and IsoLinux

[Stefan Bucur]

Hello again,

On Sun, Mar 15, 2009 at 1:16 PM, Thomas Schmitt <scdbackup at gmx.net> wrote:
> Hi,
>
> Stefan Bucur wrote:
>> contains the "-R" paramter, which enables Rock Ridge information to be
>> included in the ISO. However, according to the ISOLINUX documentation
>> [1], it "only uses the plain ISO 9660 filenames, i.e. it does not
>> support Rock Ridge or Joliet filenames.". Therefore, the ISO image you
>> built may not work as expected with ISOLINUX (maybe it does not hang
>> from the beginning, but you can expect strange behavior, from time to
>> time, as it just happened).
>
> This theory would mean trouble for my own
> project which produces ISO 9660 with Rock Ridge
> unconditionally.
> I doubt it for now, because:
>
> - Rock Ridge images with ISOLINUX booted in my
>  tests from CD, DVD and USB sticks (the latter
>  only if the BIOS is willing to boot that way
>  in general).
>
> - Rock Ridge entries reside in the ISO directory
>  records as a kind of trailing garbage.
>  First come the ISO 9660 data, then in the
>  System Use Are come entries under the SUSP
>  protocol which also governs Rock Ridge.
>  It is hard to imagine why a ISO-only reader
>  should not just ignore the extra data.

Thomas, you're right. Now I tested the ISO built with the -R option
and everything still works, so Rock Ridge information doesn't have
anything to do with the issue. Moreover, hpa's "-l" parameter enables
longer file names and you don't even have to stick with the 8.3 naming
convention.

>
>
> Matthijs ter Woord wrote:
>>  mkisofs -R ... -hard-disk-boot ...
>
> Can it be the option -hard-disk-boot which makes
> the difference ? At least it seemed not be needed
> with Stefan's test:
>> mkisofs -o ../Boot.iso -b isolinux.bin -c isolinux.cat -no-emul-boot
>> -boot-load-size 4 -boot-info-table .

Yes, this might be the real cause of trouble. However, using the most
recent version of isolinux.bin, I get the following messages when
trying to build with -hard-disk-boot:

I: -input-charset not specified, using utf-8 (detected in locale settings)
Size of boot image is 4 sectors -> Emulating a hard disk
genisoimage: Warning: boot image './isolinux.bin' MBR is not a boot sector.
Warning: partition not marked active.
Warning: partition does not start at 0/1/1.
Warning: image size does not match geometry (4233034)
genisoimage: Boot image './isolinux.bin' has multiple partitions.

The ISO image gets only 34K, and cannot boot. Matthijs, where did you
take your isolinux.bin file from?

>
>
> I have to admit that i know only the ISO/RR
> side of the topic of this thread.
> So i have few idea what goes on after the BIOS
> hopped from El Torito to ISOLINUX.
> About mkisofs -hard-disk-boot i know just what is
> written in the man page.

Well, I'm not familiar at all with the ISO standard details (today is
the first time I dig deeper into the topic) and I showed you what I
found to be working and tried to deduce what was the cause of the
original issue based on what I found on the ISOLINUX wiki page. So
thank you for pointing me out the problems with my argument :)

Cheers,
Stefan